An image of a Mishimoto performance intercooler on a workbench while an engineer works on a vehicle in the background.

How Does an Intercooler Work?

Have you ever wondered what that metal component in front of your radiator is, or maybe that thing sitting on top of your engine? If you drive a turbocharged car, chances are you’re looking at your vehicle’s intercooler. So, what does an intercooler do?

Intercoolers play a crucial role in ensuring the performance, efficiency, and longevity of turbocharged engines. As air is compressed in forced induction systems, it heats up, reducing its density and oxygen content. By cooling the air before it reaches the engine, intercoolers improve combustion efficiency, resulting in increased power and better fuel economy. This cooling process is essential in combating the heat generated by turbochargers, which can reach extreme temperatures during operation. Without an intercooler, an engine risks losing power potential and may be prone to detonation and premature wear.

How Intercoolers Work

An intercooler acts as a heat exchanger. As hot, compressed air from the turbocharger or supercharger flows through the intercooler, it passes over internal fins that are cooled by ambient air (in the case of air-to-air intercoolers) or a separate coolant system (in air-to-water intercoolers). The heat from the compressed air is transferred to these fins, allowing the cooler, denser air to exit the intercooler and enter the engine’s intake manifold. This process not only maximizes engine performance but also helps maintain engine reliability by reducing thermal stress.

An image of a performance Mishimoto intercooler installed on the front of a car with its bumper removed.

Types of Intercoolers

There are two primary types of intercoolers: air-to-air and air-to-water. Each has its strengths and specific applications, making them suitable for different vehicle setups and performance goals.

Air-to-Air Intercoolers

Air-to-air intercoolers rely on ambient airflow to dissipate heat. As compressed air moves through the intercooler, external airflow, typically generated by vehicle motion or a fan, cools the internal fins. These intercoolers are straightforward in design, highly efficient in appropriate conditions, and require no additional cooling systems. They’re commonly used in performance cars and trucks due to their simplicity and reliability.

A graphic showing how an air-to-air intercooler functions.

However, their effectiveness can be influenced by external factors such as vehicle speed, ambient temperature, and intercooler placement. For instance, a front-mount air-to-air intercooler, positioned in the grille area, benefits from maximum airflow but may require longer piping, leading to increased turbo lag. On the other hand, a top-mount intercooler, often located above the engine, reduces piping length but may suffer from heat soak due to its proximity to the engine.

Air-to-Water Intercoolers

Air-to-water intercoolers use a liquid coolant to transfer heat away from the compressed air. These systems typically include a heat exchanger, a pump, and a reservoir to circulate the coolant. They’re highly effective at maintaining consistent intake temperatures, even in extreme conditions, making them ideal for high-performance and racing applications.

A graphic showing how an air-to-water intercooler works.

While air-to-water systems are more compact and can be mounted in flexible locations, they come with increased complexity, weight, and cost. The added components, such as the coolant reservoir and pump, require more maintenance and space, which can be a drawback for daily-driven vehicles.

Comparing Front-Mount and Top-Mount Intercoolers

When choosing an intercooler setup, the placement is just as important as the type. Front-mount and top-mount intercoolers each have distinct advantages and trade-offs that cater to different performance needs and vehicle designs.

Front-Mount Intercoolers (FMIC)

Front-mount intercoolers are positioned in the front grille area, taking advantage of the coolest and most direct airflow. This placement allows for maximum heat dissipation, making FMICs highly effective in reducing intake air temperatures, especially during prolonged, high-speed driving or heavy load conditions. FMICs are commonly found in high-performance cars, trucks, and SUVs where power and cooling efficiency are paramount.

Blue Ford Focus RS fitted with a performance intercooler.

However, the long piping required to connect the intercooler to the turbocharger and intake manifold can introduce turbo lag. This occurs because the turbocharger needs to pressurize a larger volume of air, delaying throttle response. Additionally, the placement of an FMIC can sometimes obstruct airflow to the radiator or other cooling components, requiring careful design to prevent overheating.

Top-Mount Intercoolers (TMIC)

A top-mount performance Mishimoto intercooler.

Top-mount intercoolers are placed above the engine, often directly connected to the turbocharger. This setup minimizes piping length, resulting in faster throttle response and reduced turbo lag. TMICs are particularly popular in vehicles like the Subaru WRX, where the design accommodates a hood scoop to direct airflow over the intercooler.

While TMICs offer quicker response times, they’re more prone to heat soak. The proximity to the engine means that, during extended periods of operation or in hot climates, the intercooler can absorb heat from the engine bay, reducing its efficiency. To mitigate this, many vehicles incorporate heat shields or ducting to improve cooling.

Choosing the Right Intercooler for Your Vehicle

Selecting the ideal intercooler depends on your vehicle’s design, intended use, and performance goals. For daily drivers and light-duty applications, an air-to-air intercooler is often sufficient, offering a balance of simplicity, reliability, and performance. Front-mount intercoolers are ideal for vehicles prioritizing maximum cooling efficiency, while top-mount setups suit applications where turbo lag must be minimized.

For high-performance or racing vehicles, air-to-water intercoolers provide superior and consistent cooling but come with increased complexity and cost. Ultimately, the decision should align with the vehicle’s overall design and the driver’s specific needs.

The Importance of Quality Intercooler Design

Regardless of the type or placement, the quality of an intercooler’s design significantly impacts its performance. While OEM intercoolers are often sufficient for casual driving in the short-term, they often aren’t up to par for performance driving, heavy towing, or longevity. High-quality intercoolers feature efficient core designs, durable materials, and precise engineering to optimize heat transfer while minimizing pressure drop. A poorly designed intercooler can negate the benefits of forced induction by restricting airflow or failing to adequately cool the intake air.

BMW with its hood open showcasing the engine bay.

Upgrading to a performance intercooler can unlock additional horsepower and improve reliability, especially in modified vehicles with increased boost levels. That’s why our engineers take special care when designing our performance intercoolers. We ditch the plastic end tanks often found on OEM intercoolers that are prone to crack and break after repeated heat cycles, instead using more durable materials such as cast aluminum. We typically opt for an offset fin design as opposed to straight fins, allowing for more surface area to enhance heat dissipation. We take a long, hard look at the particular use case for a vehicle and choose between a tube-and-fin or bar-and-plate core for optimal performance, and we make sure to rigorously test all of our intercoolers in controlled conditions. Lastly, all of our intercoolers come backed by the Mishimoto Lifetime Warranty, so you can upgrade with peace of mind.